This is a proposal to study the determinants of family formation. We formulate and evaluate a model of cohabitation and marriage which includes influences from both young adults and their parents. We posit that entrance into cohabiting and marital unions is influenced by many dimensions of the family, socioeconomic, and religious experiences and attitudes of both young people and their parents. One contribution of our research is the examination of many important determinants of union formation that have received little previous attention. A second contribution is the expansion of knowledge about the determinants of cohabitation, an aspect of union formation that has only recently been studied empirically. A third is the analysis of union formation across a wide age range, which permits examination of the interaction of causal influences with age. A fourth aim is the explication of the causal mechanisms and processes affecting cohabitation and marriage. A final aim is the examination of the determinants of non-marital fertility. We will investigate complex causal pathways linking the experiences and attitudes of parents and children to the family formation of the children. Data for this research come from a panel study of parents and children that was designed explicitly for the purpose of studying the determinants of family formation. The data set includes eight waves of interviews with mothers extending across the 31 years from 1962 to 1993. Each of these mothers had given birth to a child in 1961, and these children were interviewed when they were 18, 23, and 31. The data set includes an extensive array of predictor variables from both parents and children and complete cohabitation and marriage histories from the children. The parental and individual determinants of union formation will be examined from a life course perspective using hazard models. The proposed research is a cooperative project between the University of Michigan and Pennsylvania State University. Parallel proposals are being submitted by the two institutions.